BRUSSELS • A man wielding a knife was shot dead after wounding a soldier in Brussels in an "attempted terrorist murder" while, in London, counter-terror experts were investigating a similar attack on police near Buckingham Palace.

Belgian prosecutors said last Friday the attacker yelled "Allahu Akbar" (God is great) during the assault before being shot by a soldier in the centre of the city, which has been on high alert since last year's carnage at the airport and on the metro.

Overnight, police raided the suspect's home in Bruges, north-west Belgium, with federal prosecutors opening an investigation into "attempted terrorist murder", a statement said.

During the attack near the Grand Place in central Brussels at 8pm (2am yesterday Singapore time) last Friday, the man rushed at several soldiers from behind and struck them with a knife, prompting one of them to open fire.

"The man was hit and died shortly afterwards in hospital from his wounds," the prosecutors' statement said.

As well as the knife, police found a replica gun and two copies of the Quran on him. The assailant was a Belgian national of Somali origin who was born in 1987, the authorities confirmed. He arrived in the country in 2004 and was granted Belgian nationality in 2015.

Although not known for any terror-related activities, he had an assault and battery charge on his record from February, the statement said.

Less than two hours later, two British police officers were slightly injured while arresting a man with a large knife outside Buckingham Palace in London.

The 26-year-old attacker, who was initially detained on suspicion of causing grievous bodily harm and assaulting police, was later arrested under the Terrorism Act 2000.

"Detectives from the Metropolitan Police's Counter Terrorism Command are now investigating the incident," police said.

The Queen was at her Balmoral residence in Scotland at the time.

The incidents follow vehicle attacks in Spain on Aug 17 which killed 15 people and were claimed by the Islamic State in Iraq and Syria group, and another stabbing spree in Finland which left two dead and eight wounded.

Tens of thousands of Spaniards and foreigners were expected on the streets of Barcelona yesterday in a defiant march against terror after the deadly vehicle rampages.

Spanish Prime Minister Mariano Rajoy has called on Spaniards to turn up in force to show their "love" and solidarity with Catalonia, where the rampages took place.

Also present would be King Felipe VI, the first Spanish sovereign to take part in a demonstration since the monarchy was re-established in 1975 after the death of dictator Francisco Franco.

Much of Europe is on high alert following a string of major attacks over the past two years - most of which have been claimed by, or blamed on, militants.

One of the two soldiers targeted in Brussels was "slightly" wounded, the prosecutors said.

"All our support for our military," tweeted Belgian Prime Minister Charles Michel, saying the situation was being closely monitored.

AGENCE FRANCE-PRESSE